package com.jay.lang.clazz;

import java.util.Random;

public class ThreadLocalCls implements Runnable {
	// 创建线程局部变量studentLocal，在后面你会发现用来保存Student对象
	private final static ThreadLocal<Student> studentLocal = new ThreadLocal<Student>();

	public static void main(String[] agrs) {
		ThreadLocalCls td = new ThreadLocalCls();
		Thread t1 = new Thread(td, "a");
		Thread t2 = new Thread(td, "b");
		t1.start();
		t2.start();
	}

	public void run() {
		accessStudent();
	}

	/**
	 * 示例业务方法，用来测试
	 */
	public void accessStudent() {
		// 获取当前线程的名字
		String currentThreadName = Thread.currentThread().getName();
		System.out.println(currentThreadName + " is running!");
		// 产生一个随机数并打印
		Random random = new Random();
		int age = random.nextInt(100);
		System.out
				.println("thread " + currentThreadName + " set age to:" + age);
		// 获取一个Student对象，并将随机数年龄插入到对象属性中
		Student student = getStudent();
		student.setAge(age);
		System.out.println("thread " + currentThreadName
				+ " first read age is:" + student.getAge());
		try {
			Thread.sleep(500);
		} catch (InterruptedException ex) {
			ex.printStackTrace();
		}
		System.out.println("thread " + currentThreadName
				+ " second read age is:" + student.getAge());
	}

	protected Student getStudent() {
		// 获取本地线程变量并强制转换为Student类型
		Student student = (Student) studentLocal.get();
		// 线程首次执行此方法的时候，studentLocal.get()肯定为null
		if (student == null) {
			// 创建一个Student对象，并保存到本地线程变量studentLocal中
			student = new Student();
			studentLocal.set(student);
		}
		return student;
	}

	class Student {
		private int age = 0; // 年龄

		public int getAge() {
			return this.age;
		}

		public void setAge(int age) {
			this.age = age;
		}
	}

}
